The understanding of how gene expression is controlled is fundamental to discovering the mechanisms involved in normal and abnormal cellular growth and differentiation in all biological systems. Recent information suggests that a large number of positive and negative regulatory factors are operative in controlling individual gene activity in bacteria as well as in multicellular organisms. it is becoming increasingly clear that the interplay of these regulatory components, rather than their individual activities, is critical to gene function. With this in mind we wish to continue our study of the factors involved in the control of the ilvBN and ompB operons of Escherichia coli. The goals of this work are twofold: First, to more thoroughly understand the interaction between integration host factor (IHF) and the ilvBN attenuation system. This work will involve in vivo and in vitro analysis of the transcriptional antitermination activity of IHF in the ilvBN leader. The second goal is to understand the role in ompB expression of a number of DNA binding proteins that interact with the ompB promoter region. A combined biochemical and genetic approach will be used in an attempt to determine the physiological significance and the precise molecular mechanisms involved in the interplay of these proteins in the regulation of ompB transcription.